This is where the artist explains his interpretation of the element and the science behind the picture. Where the element is most commonly found in nature, and how it is sourced commercially. Atomic radius, non-bonded Half of the distance between two unbonded atoms of the same element when the electrostatic forces are balanced. These values were determined using several different methods. Covalent radius Half of the distance between two atoms within a single covalent bond.
Values are given for typical oxidation number and coordination. Electron affinity The energy released when an electron is added to the neutral atom and a negative ion is formed. Electronegativity Pauling scale The tendency of an atom to attract electrons towards itself, expressed on a relative scale.
First ionisation energy The minimum energy required to remove an electron from a neutral atom in its ground state. The oxidation state of an atom is a measure of the degree of oxidation of an atom.
It is defined as being the charge that an atom would have if all bonds were ionic. Uncombined elements have an oxidation state of 0. The sum of the oxidation states within a compound or ion must equal the overall charge.
Data for this section been provided by the British Geological Survey. An integrated supply risk index from 1 very low risk to 10 very high risk. This is calculated by combining the scores for crustal abundance, reserve distribution, production concentration, substitutability, recycling rate and political stability scores.
The percentage of a commodity which is recycled. A higher recycling rate may reduce risk to supply. The availability of suitable substitutes for a given commodity. The percentage of an element produced in the top producing country. The higher the value, the larger risk there is to supply. The percentage of the world reserves located in the country with the largest reserves. A percentile rank for the political stability of the top producing country, derived from World Bank governance indicators.
A percentile rank for the political stability of the country with the largest reserves, derived from World Bank governance indicators. Specific heat capacity is the amount of energy needed to change the temperature of a kilogram of a substance by 1 K.
A measure of the stiffness of a substance. It provides a measure of how difficult it is to extend a material, with a value given by the ratio of tensile strength to tensile strain. A measure of how difficult it is to deform a material. It is given by the ratio of the shear stress to the shear strain. A measure of how difficult it is to compress a substance. It is given by the ratio of the pressure on a body to the fractional decrease in volume.
A measure of the propensity of a substance to evaporate. It is defined as the equilibrium pressure exerted by the gas produced above a substance in a closed system. This Site has been carefully prepared for your visit, and we ask you to honour and agree to the following terms and conditions when using this Site.
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Jump to main content. Periodic Table. Glossary Allotropes Some elements exist in several different structural forms, called allotropes. Discovery date Discovered by Nicholas Louis Vauquelin Origin of the name The name is derived from the Greek 'chroma', meaning colour.
Glossary Group A vertical column in the periodic table. Fact box. Glossary Image explanation Murray Robertson is the artist behind the images which make up Visual Elements. Appearance The description of the element in its natural form.
Biological role The role of the element in humans, animals and plants. Natural abundance Where the element is most commonly found in nature, and how it is sourced commercially. Uses and properties. Image explanation. A safe amount is about 1 milligram per day, according to the RSC. Foods such as brewer's yeast, wheat germ and kidney are rich in chromium. However, it is poisonous in excess. In the film "Erin Brockovich," Julia Roberts portrays an environmental activist and legal clerk who leads a case against a gas and electric company for contaminating drinking water with chromium VI , a toxic compound known to cause cancer , according to the U.
Though Brockovich won the case in real life and in the movie, scientists have criticized her lack of evidence showing that chromium VI , and not other factors, was the cause of the numerous health issues including cancer in the community of Hinkley, Calif. However, several studies in the past few years have linked chromium VI in tap water to cancer and the EPA has set a drinking water concentration limit for the element to protect public health.
Excessive exposure to chromium can also cause chrome ulcers, particularly when working with it for months while chrome-plating or leather tanning, according to Emsley. Chrome ulcers are itchy and raw holes in the skin or the stomach. If dust containing chromium is inhaled, industrial workers are more prone to ulcers in the nasal cavity and lung cancer.
Additionally, a study published in European Journal of Clinical Nutrition linked high levels of urinary chromium to cardiovascular disease and diabetes. Manganese steels are extremely strong, and are used in railroad tracks, earth-moving machinery, and other applications. Potassium permanganate, KMnO 4 , is a deeply purple crystalline substance when pure, and forms purple solutions when dissolved in water; it is a strong oxidizing agent, and is used in bleaches, disinfectants, deodorizers, and as a reagent for some reactions in organic chemistry.
Traces of manganese give amethysts, which are composed primarily of silicon dioxide, their characteristic purple color. Manganese is also an essential trace nutrient, and is involved in the action of vitamin B1 thiamine in the metabolism of carbohydrates.
Nuts and cereals have fairly high levels of manganese. Technetium is a radioactive element; the pure metal is silvery-gray in appearance, although it usually used as a grey powder. It is named for the Greek word technetos , meaning "artificial," because it was the first element to be produced artificially.
Trace amounts of technetium are found in uranium ores, where it is produced by spontaneous fission of uranium, but the element is not present in large enough quantities to be practically mined the concentration is estimated at about 1 nanogram per kilogram of ore.
It is also obtained from spent uranium fuel rods in nuclear reactors. Technetium is produced by the neutron bombardment of molybdenum to produce molybdenum, which then undergoes beta-decay with a half-life of 67 hours to produce technetiumm, a metastable, excited nuclear state with a half-life of 6 hours, which emits gamma rays to form ground-state technetium Technetium is also radioactive, and is a beta-particle emitter with a half-life of , years.
There are about 56 isotopes of technetium including metastable states , and all of them are radioactive. The longest-lived isotope, technetium, has a half-life of 4. That may seem like a long time, but compared to the age of the Earth — 4. In , traces of technetium were discovered in the spectra of some types of red giant stars; this was one of the first pieces of evidence to support the theory that heavy elements were produced in stars.
Many early reports of its discovery turned out to be mistaken, being instead impure samples of other, known elements.
The element was finally discovered in by Emilio Segre and Carlo Perrier at the University of Palermo in Italy, in a sample of molybdenum that had been bombarded with deuterium hydrogen-2 , producing technetium The element may have been discovered earlier by Walter Noddack, Otto Berg, and Ida Tacke in , who bombarded a sample of columbite [ Fe, Mn Nb, Ta 2 O 6 ] with a beam of electrons, and reported an X-ray signal that they believed to be element 43, which they named "masurium" after after Masuria in eastern Prussia now a part of Poland.
However, their results could not be reproduced, and their claim was not accepted; recent research indicates they they may indeed have been able to produce very small amounts of element 43 by this method after all. Technetium is used in several applications in nuclear medicine as a radioactive tracer, since it emits gamma rays that are detectable by imaging devices. It is obtained from a technetiumm generator , also known as a "technetium cow," in which radioactive molybdenum with a half-life of 67 hours is adsorbed onto an alumina chromatography column; the molybdenum decays to water-soluble technetiumm, which is extracted from the column by passing a saline solution through it the process is naturally referred to as "milking" , whereupon it can be mixed with the reagent that is appropriate for the particular imaging technology to be used.
In immunoscintigraphy , radioactive technetiumm is incorporated into a monoclonal antibody which binds to cancer cells; this technique is used to detect intestinal cancers, which are difficult to locate by other techniques. In combination with tin compounds, technetiumm binds to red blood cells, and can be used to map the circulatory system; this is particularly useful in diagnosing some types of congestive heart failure and in determining the damage done to the heart muscle by a heart attack.
Ammonium pertechnate, NH 4 TcO 4 , and other technetium salts, can be used as corrosion inhibitors for steel, however, because of the radioactivity of technetium, this is useful only in closed systems.
Rhenium, id a silvery-white, hard metal. It is resistant to corrosion, but slowly tarnishes in moist air. It is named for named for the Latin word for the Rhine River, Rhenus. It is found in the Earth's crust at a concentration of 0.
It occurs as an impurity in molybdenite, copper sulfide, and other ores. Rhenium is used in alloys with tungsten and molybdenum to make filaments for ovens and lamps, and is also used in electroplating jewelry. It is also used in combination with platinum to make catalysts for generating high-octane gasoline from crude oil.
Rhenium was discovered by Walter Noddack, Otto Berg, and Ida Tacke in , as a trace element in columbite, gadolinite, molybdenite and platinum ores. It was the last of the naturally occurring elements to be discovered, in part because of its extremely low concentration in the Earth's crust and because it is not concentrated in any unique minerals or ores. Bohrium is a synthetic element, produced by the cold fusion of bismuth and chromium The longest-lived isotope, bohrium, has a half-life of 0.
The IUPAC concluded that the GSI group should be awarded credit for the discovery, but both groups were allowed to collaborate on choosing a name for the element.
They chose "neilsbohrium" in honor of the Danish physicist Niels Bohr; this was shortened to "bohrium" in The elements in each period of these groups are very similar in their chemical and physical properties. The Group 8 elements usually have the electron configuration n -1 d 6 ns 2 , the Group 9 elements usually have the electron configuration n -1 d 7 ns 2 , and the Group 10 elements usually have the electron configuration n -1 d 8 ns 2.
Iron in its pure form is a malleable, ductile, silvery metal. The name comes from the Anglo-Saxon word for the metal, iren ; the chemical symbol "Fe" is derived from the Latin word for iron, ferrum.
It is the fourth most abundant element in the Earth's crust, having a concentration of about 4. Iron compounds are extremely common: iron II oxide, or ferrous oxide, FeO, is the third most abundant compound in the Earth's crust, having a concentration of 89, ppm, and iron III oxide, or ferric oxide, Fe 2 O 3 , is the seventh most abundant compound, with a concentration of ppm. According to the dynamo theory, convection current in the molten iron and nickel of the outer core give rise to Earth's magnetic field.
Iron is the final product of nuclear fusion in average-sized stars like the Sun; the fusion of iron requires an input of energy, and in these stars, iron accumulates in their centers as their nuclear fuel becomes spent. Iron has been used by humans at least as far back as BC, mostly for ceremonial purposes because of the difficulty in obtaining it in its pure form. The iron that was used in this way was often recovered from meteorites. The processing of smelting iron from its ores was discovered in Asia Minor around BC.
Iron ore from Magnesia in Lydia, Asia Minor, was discovered to attract other pieces of iron; this ore was named "magnetite" and the attractive pieces of metal were named "magnets" after their country of origin. Iron is extracted from its ores by smelting the ores in a blast furnace with coke, a low-ash carbonaceous residue obtained from bituminous coal, and limestone calcium carbonate, CaCO 3 , which is used as a flux to melt impurities in the ore.
This is further refined to produce either pure iron or an alloy. Pure iron is a fairly soft metal, and corrodes easily, and is often alloyed with other metals to improve its strength and durability. Steel is iron containing from between 0. These steels can be alloyed with other metals, such as nickel, tungsten, vanadium, and manganese, to make extremely durable materials.
Many of the transition metals oxidize to produce metal oxides that adhere tightly to the exposed metal, protecting the metal surface against further oxidation. When iron oxidizes, however, the iron III oxide, Fe 2 O 3 , that is generated flakes off of the metal surface, exposing more of the metal to further oxidation. The oxygen is reduced to water by the electrons released by the oxidation of iron, since the electrons are easily carried through the conductive metal.
Iron's longevity can be extended by coating it with zinc to produce galvanized iron. Zinc is more easily oxidized than iron, and so under conditions in which a metal can be oxidized, the zinc is oxidized instead of iron. Galvanized iron is used in car parts, outdoor fences, and other applications. The same idea is exploited in tinplate , in which a sheet of iron is coated with a thin layer of tin.
This is used in the manufacture of tin cans. In many cases, it is unnecessary to coat the entire iron surface with another metal; instead, the iron is placed in electrical contact with a "sacrificial anode" made of an easily oxidized metal such as magnesium, zinc, or aluminum.
This process is used to protect underground steel pipelines, boat hulls and propellers, and water heaters. These metal anodes are usually designed to be easily replaceable, so that when they are used up i. Iron III oxides are used to make magnetic storage media. Iron is an essential nutrient for almost all living organisms.
Iron is also involved in the function of many of the body's enzymes, including those which synthesize DNA and those which metabolize carbohydrates. Iron is also bound by the transferrin protein, which carries iron between various cells in the body; it also acts as an antibiotic by preventing the uptake of iron by invading bacteria.
Iron is easily obtained in the diet, from foods such as red meat, fish, poultry, liver, breakfast cereals, wine, lentils, beans, black-eyed peas, leafy vegetables, tofu, peanut butter, raisins, bread, and eggs.
Despite the nutritional recommendations from the "Popeye" cartoons, spinach is not actually a good source of iron — even though it contains 2.
Cobalt is a hard, lustrous bluish-gray metal. It is named for the German word for "goblin," kobold , because of the toxic fumes of arsenic that were produced when silver miners heated the ore smaltite, CoAs 2 , mistaking it for silver ore. It is found in the Earth's crust at a concentration of 20 ppm, making it the 32nd most abundant element. Cobalt is found in the ores cobaltite [ Co, Fe AsS] and erythrite [cobalt III arsenate, Co 3 AsO 4 2 ], although it is more commonly obtained as a by-product of nickel and copper mining.
Cobalt has been used to produce deeply blue colors in glass and pottery since the time of the Ancient Egyptians.
Today, cobalt is used in many types of alloys, ceramics, stained glass known as cobalt glass , magnets, and magnetic recording media. Cobalt is not as magnetic as iron, but its magnetic properties are retained at higher temperatures than iron; it is alloyed with aluminum and nickel to make strong, permanent Alnico magnets.
Radioactive cobalt is made by bombarding cobalt with neutrons in a nuclear reactor. Cobalt has a half-life of 5. Cobalt used used as a radiation source in some medical equipment, and is also used in irradiating food and detecting structural defects in metals. Replacing the hydroxide anions with chloride anions forms the blue complex [CoCl 4 ] Cobalt is essential in the diet because it is incorporated into Vitamin B 12 cyanocobalamin , which is necessary for the prevention of pernicious anemia.
Nickel is a hard, malleable, silvery metal. The name is derived from the German word kupfernickel , meaning "Old Nick's copper" i. It is found in the Earth's crust at a concentration of 80 ppm, making it the 23rd most abundant element. Because of its high resistance to oxidation, it is frequently used in coins. Nickel is more commonly used in alloys rather than as the pure metal.
Pure nickel is ferromagnetic, and is used in some permanent magnets, such as Alnico magnets which are composed of an alloy of aluminum, nickel, and cobalt. Nickel aluminide, Ni3Al, is an unusual alloy which is six times stronger than stainless steel, and becomes stronger at higher temperatures, making it of potential use in rocket engines.
Nickel powder or Raney nickel a nickel-aluminum alloy are used as catalysts for the production of hydrogenated oils , in which unsaturated fats, which contain carbon-carbon double bonds, and tend to be liquids at room temperature, are reacted with hydrogen gas to produce saturated fats, which contain carbon-carbon single bonds only, and tend to be solids at room temperature. The hydrogen and unsaturated fats are adsorbed onto the surface of the metal, which slightly weakens the hydrogen-hydrogen bonds and the carbon-carbon double bond; when the hydrogen "bumps" against the weakened bond, the hydrogen atoms are added to the carbon-carbon double bond, producing a single bond, and the saturated product drifts away from the metal surface, leaving it free to react with more of the reactants.
This process is used in the production of shortening from vegetable oils, and the production of margarines and other spreads. The battery can be recharged, using an external source of electricity to run the reactions in reverse, allowing the battery to be reused.
Ruthenium is a silver-gray, extremely brittle, and stable metal. It named from the Latin word for Russia, Ruthenia. It is found in the Earth's crust at a concentration of 1 ppb, making it the 74th most abundant element. It is found in the ores laurite [ruthenium sulfide, RuS 2 ], ruarsite [ruthenium arsenic sulfide, RuAsS], and ruthenarsenite [ Ru,Ni As], although it is usually obtained as a by-product from the refining of nickel and platinum. Ruthenium is used in the electronics industry in some electrical contacts and chip resistors.
It is also used in the anodes used to produce chlorine in electrolytic cells. It is also used in alloys with platinum and palladium in jewelry to harden the metals. Rhodium is a silvery, hard, unreactive metal. It is named from the Greek word for rose, rhodon , because of its red-colored salts. It is found in some areas as the free metal, and in the ore rhodplumsite [ Rh 3 Pb 2 S 2 ], and is also found in some platinum ores. Adverse effects of the hexavalent form on the skin may include ulcerations, dermatitis, and allergic skin reactions.
Inhalation of hexavalent chromium compounds can result in ulceration and perforation of the mucous membranes of the nasal septum, irritation of the pharynx and larynx, asthmatic bronchitis, bronchospasms and edema. Respiratory symptoms may include coughing and wheezing, shortness of breath, and nasal itch.
Carcinogenicity- Chromium and most trivalent chromium compounds have been listed by the National Toxicology Program NTP as having inadequate evidence for carcinogenicity in experimental animals.
According to NTP, there is sufficient evidence for carcinogenicity in experimental animals for the following hexavalent chromium compounds; calcium chromate, chromium trioxide, lead chromate, strontium chromate,and zinc chromate.
International Agency for Research on Cancer IARC has listed chromium metal and its trivalent compounds within Group 3 The agent is not classifiable as to its carcinogenicity to humans. ACGIH has classified chromium metal and trivalent chromium compounds as A4,not classifiable as a human carcinogen.
There are several different kinds of chromium that differ in their effects upon organisms. Chromium enters the air, water and soil in the chromium III and chromium VI form through natural processes and human activities. The main human activities that increase the concentrations of chromium III are steal, leather and textile manufacturing.
The main human activities that increase chromium VI concentrations are chemical, leather and textile manufacturing, electro painting and other chromium VI applications in the industry. These applications will mainly increase concentrations of chromium in water. Through coal combustion chromium will also end up in air and through waste disposal chromium will end up in soils.
Most of the chromium in air will eventually settle and end up in waters or soils. Chromium in soils strongly attaches to soil particles and as a result it will not move towards groundwater.
In water chromium will absorb on sediment and become immobile. Only a small part of the chromium that ends up in water will eventually dissolve.
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